The design of distributed data communications network topologies has been practiced for many years. The need for a comprehensive method for designing a distributed data communication network results from the complexity of such a system. A distributed data communications network is a hierarchical system of hardware components arranged so that each hardware device is connected, directly or indirectly, to every other device. At the lowest level are user terminals or hosts, which form part of the local access network. These terminals are linked to one or more concentrators, which are statistical multiplexers with protocol conversion functionalities with several low data rate input, data lines, and a fewer number of high data rate, output data lines. The concentrators form the second level of the hierarchy and, together with the terminals, form the access network.
The concentrators, which may be connected to other concentrators in a hierarchical fashion, are ultimately connected to the backbone, which forms the highest level in the hierarchy. The backbone consists of high speed, high capacity links that terminate at backbone nodes. A backbone node consists of one or more devices, and includes at least one switching device for routing traffic within the backbone. The data traffic from the concentrators enters the backbone at a backbone node.
The larger number of terminal locations typically present in a distributed data communications network means that there is a need for a method for aggregating terminals into clusters in order to most efficiently and economically construct and evaluate the network. These clusters can be treated as virtual terminals which simplifies the subsequent analysis by reducing the number of individual terminals that must be considered. Alternatively, these clusters can be considered as potential locations for concentrators or backbone nodes.
Existing methods for aggregating the terminals of a distributed data communications network into clusters have deficiencies that are overcome by the present invention. Other systems for aggregating terminals into clusters have been so vendor-specific that they could only be used to construct a network with equipment provided by a limited number of vendors, and in some cases with the equipment provided by only a single vendor. Still other generic methods, while not limited to specific vendors' hardware, do not address the hardware capabilities with sufficient detail to permit the selection of particular hardware components.